1. Field of the Invention
The present invention relates to an image sensor, a method of manufacturing the same, and a camera module having the same.
2. Description of the Related Art
With the recent development of mobile terminals such as portable phones and personal digital assistants (PDAs), the mobile terminals provide a phone call function and are used as multi-convergence devices. The most representative of the multi-convergence is a camera module. The resolution of the camera module changes from 300,000 pixels (VGA) to 8,000,000 pixels. Moreover, the camera module provides various additional functions, such as auto-focusing (AF) and optical zoom. Generally, camera modules are applied to various IT devices, such as camera phones, smart phones, and mobile communication terminals.
The camera modules are manufactured by using main parts of charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image sensors. Incident light transmitted through the lens is condensed by the image sensor and is stored as data in the memory. The stored data is displayed as an image through a display medium, such as liquid crystal display (LCD) or PC monitor.
Hereinafter, a conventional image sensor module and a camera module having the same will be described with reference to FIGS. 1 to 3.
FIG. 1 is an exploded perspective view of a conventional chip-on-board (COB) camera module. FIG. 2 is an exploded perspective view of a conventional chip-on-film (FOB) camera module. FIG. 3 is an exploded perspective view of a conventional socket-type camera module.
As shown in FIG. 1, the conventional COB camera module includes a rigid printed circuit board (RPCB) 11, an image sensor 12, an infrared ray (IR) cut-off filter 13, a housing 14, and a lens barrel 15.
The RPCB 11 has various electronic parts and semiconductor elements mounted thereon. In particular, the RPCB 11 has passive elements 17 mounted on the top surface thereof at one side of the image sensor 12, the passive elements 17 preventing noise of the camera module.
The image sensor 12 is composed of a CCD or CMOS image sensor and converts light into an electrical signal, the light being incident through the IR cut-off filter 13 via a lens group L.
The IR cut-off filter 13 is installed on a lower step portion of the housing 14 so as to cut off long-wavelength infrared rays included in the light incident on the image sensor 12.
The lens barrel 15 has the lens group L mounted therein and is assembled to the housing through a screw method.
As shown in FIG. 2, the conventional COF camera module includes a flexible printed circuit board (FPCB) 21, an image sensor 22, an IR cut-off filter 23, a housing 24, and a lens barrel 25.
The FPCB 21 has a rectangular window 21a formed therein, and electronic parts such as capacitors and resistors for driving the image sensor 22 are mounted on the FPCB 21. In particular, passive elements 27 for preventing noise of the camera module are mounted on the top surface of the FPCB 21 at one side of the window 21a. 
The image sensor 22 is composed of a CCD or CMOS image sensor and is mounted on the bottom surface of the FPCB 21 so as to convert light into an electrical signal, the light being incident through the window 21a of the FPCB 21.
The IR cut-off filter 23 is installed on the top surface of the FPCB 21 so as to cut off long-wavelength infrared rays in the light incident on the image sensor 22 through the window 21a of the FPCB 21.
The lens barrel 25 has a lens group L mounted therein and is assembled to the housing 24 through a screw method.
The FPCB 21 has a connector (not shown) installed on an extended end thereof, the connector serving to electrically connect the camera module to an external device.
The conventional socket-type camera module shown in FIG. 3 is implemented by modifying the conventional COB camera module shown in FIG. 1. In the socket-type camera module, a ceramic substrate 31 is used instead of the FPCB, in order to apply a side contact method.
That is, the socket-type camera module includes a ceramic substrate 31, an image sensor 32, an IR cut-off filter 33, a housing 34, and a lens barrel 35. The ceramic substrate 31 has a pad for connection with a terminal of a socket, the pad being formed in a groove formed on a side surface of the ceramic substrate 31. The groove is formed in the lower portion of the side surface of the ceramic substrate 31 such that when an adhesive for coupling the ceramic substrate 31 and the housing 34 is applied, the applied adhesive is prevented from being flowing into the pad.
On the center of the top surface of the ceramic substrate 31, the image sensor 32 is mounted. Further, on the edge of the top surface, various electronic parts and semiconductor elements for driving the image sensor 32 are mounted. In particular, passive elements 37 for preventing noise of the camera module are mounted on the top surface of the ceramic substrate 31 at one side of the image sensor 32.
However, the above-described camera modules have the following problems.
The camera modules require the passive elements 17, 27, and 37 for preventing noise. Therefore, as the passive elements 17, 27, and 37 are mounted on the top surfaces of the substrates 11, 21, and 31 at one side of the image sensors 12, 22, and 32, the size of the camera modules inevitably increases.
That is, since a space for mounting the passive elements 17, 27, and 37 as well as the image sensors 12, 22, and 32 is needed, the size of the substrates 11, 21, and 31 increases.
Further, as the size of the substrates 11, 21, and 31 increases toward the side where the passive elements 17, 27, and 27 are mounted, the center of the lens group L is not positioned in the center of the substrates 11, 21, and 31.
To solve such a problem, when the size of the substrates 11, 21, and 31 at an opposite side to the side where the passive elements 17, 27, and 37 are mounted is increased, the size of the substrates 11, 21, and 31 further increases.
The passive elements 17, 27, and 37 may be mounted on the bottom surface of the respective substrates 11, 21, and 31. However, such a construction cannot be applied to the socket-type camera module, and the height of the camera module inevitably increases. Further, when the camera module is assembled into an external device, short circuit may occur.
Further, in the conventional socket-type camera module, the expensive ceramic substrate 31 should be used for the side contact method. Therefore, a manufacturing time and cost increases.